# Outcome API and MCP for outcome-based software | Spoolis for developers Canonical HTML: https://spoolis.com/developers. This page is also available in machine-readable Markdown. Build outcome-based products on the outcome API and MCP: freeze what counts, bring your own judge, and get back a signed Outcome that billing, workflows and agents can act on. ## The problem Freeze what counts, bring your own judge, and get back a signed Outcome that billing, workflows and agents can act on. REST, MCP and CLI; the sandbox needs no account. ## How it works Freeze acceptance criteria in a Spool before the work starts. Versioned, so the rule cannot shift after the fact. Deterministic checks, your model, a reviewer, or another authority. Spoolis records the verdict and where it came from. Accepted, rejected or uncertain, per unit, with earned value. Send it to billing, a workflow, or the next agent. - [Read the quickstart](/docs/quickstart) - [Bring your own judge](/docs/guides/bring-your-own-judge) - [Verify a receipt](/docs/verify-receipt) - [Try the sandbox](/new) ## What you get Ed25519 receipts. Open verifiers for JavaScript and Python check the signature and the figures with pinned trust material. Idempotent events. A correction adds a version and keeps the earlier one. History is never rewritten. A hosted MCP server, machine.md, llms.txt and a skill file, so an agent can run the whole lifecycle and continue only with accepted work. - [Spoolis Platform](/platform) - [Outcome Acceptance](/products/outcome-acceptance) - [API reference](/docs/api) - [MCP server](/docs/mcp)